Optical tracking module chip for wireless optical communication terminals

Abstract

To provide an optical tracking module for wireless optical communication terminals, which can be integrated onto one or more photonic integrated chips. The optical tracking module (102, 302) includes an optical phased array (OPA) (112, 312), an analog drive (116, 316), an integrated optical detector (118, 318), and one or more processors (114, 314). The OPA includes a plurality of array elements and a plurality of phase shifters (113, 313). The analog drive is configured to adjust the plurality of phase shifters. The integrated optical detector is configured to receive light from the OPA. The one or more processors are configured to extract signal information of an incoming beam through the OPA and control an outgoing beam using the analog drive based on the signal information. The OPA, the analog drive, the integrated optical detector, and the one or more processors are in an integrated circuit.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application is a continuation of U.S. Provisional Application No. 17 / 698,224, filed March 18, 2022, which claims the benefit of U.S. Provisional Application No. 63 / 246,605, filed September 21, 2021, and U.S. Provisional Application No. 63 / 246,599, filed September 21, 2021. The entire disclosures of these applications are incorporated herein by reference. [Background technology]

[0002] Wireless optical communications enable high throughput and long distance communications due in part to the high gain provided by the narrow angular width of the transmitted beam. However, the narrow beam also requires that it must be accurately and actively pointed to remain aligned with the terminal aperture at the remote end. This pointing can be achieved by small mirrors (e.g., MEMS or voice coil based fast steering mirror mechanisms) that are actuated to steer the beam. In other implementations, electro-optic steering of the beam with no moving parts is used to steer the beam, which offers cost, lifetime, and performance advantages. Optical Phased Arrays (OPAs) are an important technology building block with additional advantages for adaptive optics, point-to-multipoint support, and mesh network topologies. Each active element in an OPA requires electro-optic phase shifting capability. Summary of the Invention

[0003] Aspects of the present disclosure provide a free space optical communication system, i.e., an optical tracking module. The optical tracking module includes an optical phased array (OPA), an analog drive, an integrated optical detector, and one or more processors. The OPA includes a plurality of array elements and a plurality of phase shifters. The analog drive is configured to adjust the plurality of phase shifters. The integrated optical detector is configured to receive light from the OPA. The one or more processors are configured to extract signal information of an incoming beam through the OPA and, based on the signal information, control an outgoing beam using the analog drive. The OPA, the analog drive, the integrated optical detector, and the one or more processors are in an integrated circuit.

[0004] In one example, the optical tracking module is configured to connect to a modem via one or more fibers. In this example, the optical tracking module optionally includes a circulator including a first port configured to receive a signal from the first fiber, a second port configured to transmit a signal to the integrated circuit and receive a signal from the integrated circuit, and a third port configured to transmit a signal to the second fiber. In another example, the optical tracking module includes a voltage regulator. In this example, the voltage regulator is optionally configured to provide power to the integrated circuit.

[0005] In a further example, the optical tracking module is configured to communicate telemetry data to one or more separate processors external to the optical tracking module. In yet another example, the optical tracking module is configured to connect to a separate optical lens assembly that increases the aperture gain. In this example, the optical tracking module is also configured to optionally connect to a separate transceiver module that includes one or more transceivers and one or more amplifiers. In yet a further example, the optical tracking module is configured to communicate telemetry data to one or more separate processors external to the optical tracking module. In yet another example, the optical tracking module is configured to communicate to a separate optical lens assembly that increases the aperture gain. In this example, the optical tracking module is also configured to optionally connect to a separate transceiver module that includes one or more transceivers and one or more amplifiers. In yet a further example, the optical tracking module is configured to communicate to a separate transceiver module that optionally includes one or more transceivers and one or more amplifiers. 3 In this example, the optical tracking module is optionally configured to have a surface area of ​​less than 100 cm on any face. 2 is less than.

[0006] In another example, the plurality of array elements is a 32 x 32 array. In a further example, the analog drive includes a digital-to-analog converter (DAC) and an amplifier, and the one or more processors are connected to the DAC, which is also connected to the amplifier, which is also connected to the OPA. In yet another example, the integrated photodetector is connected to the one or more processors via an amplifier and an analog-to-digital converter (ADC).

[0007] Another aspect of the disclosure provides a system including a plurality of communication terminals in a network arrangement including a plurality of point-to-point relay links, each of the plurality of communication terminals including an optical tracking module having an optical phased array (OPA) including a plurality of array elements and a plurality of phase shifters, an analog drive configured to adjust the plurality of phase shifters, an integrated photodetector configured to receive light from the OPA, and one or more processors configured to extract signal information of an incoming beam via the OPA and control an outgoing beam using the analog drive based on the signal information, each of the plurality of communication terminals being lensless except for the OPA.

[0008] In one example, each communication terminal of the plurality of communication terminals is located within 100 meters of another communication terminal of the plurality of communication terminals, and each communication terminal of the plurality of communication terminals has a throughput of at least 10 Gbps to another communication terminal of the plurality of communication terminals. In another example, the network arrangement also includes one or more point-to-multipoint links. In a further example, the network arrangement at least partially includes a mesh arrangement. In yet another example, the network arrangement at least partially includes a ring arrangement. In yet a further example, the plurality of point-to-point relay links includes at least one inter-building link.

[0009] A further aspect of the present disclosure provides a method for controlling an optical phased array, the method including receiving a first optical communication beam at an optical phased array in an integrated circuit, receiving the first optical communication beam at an optical detector in the integrated circuit, generating a first signal at the optical detector based on the first optical communication beam, determining, by one or more processors in the integrated circuit, signal information of the first optical communication beam according to the first signal, transmitting, by the one or more processors, a second signal to adjust one or more phase shifters in the integrated circuit based on the determined signal information, and transmitting the second optical communication beam using the optical phased array and the one or more phase shifters. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram 100 of an optical tracking module according to an embodiment of the present disclosure. [Diagram 2] 2 is a functional flow diagram 200 of an optical tracking module according to an embodiment of the present disclosure. [Diagram 3] 3 is a block diagram 300 of a first optical tracking module and a second optical tracking module according to an embodiment of the present disclosure. [Figure 4A] 1 is a block diagram of a first communication system and a second communication system according to an aspect of the present disclosure. [Figure 4B] 1 is a pictorial diagram of a communication system according to an aspect of the present disclosure. [Diagram 5] FIG. 1 is a block diagram of a network according to an aspect of the present disclosure. [Figure 6A] 1 is a pictorial diagram of a portion of a network, according to an aspect of the present disclosure. [Figure 6B] 1 is a pictorial diagram of a portion of a network, according to an aspect of the present disclosure. [Figure 7] FIG. 1 is a flow diagram according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] overview The present technology relates to an optical tracking module for wireless optical communication terminals that may be integrated on one or more photonic integrated chips. The optical tracking module may be configured for short-range "last mile" network connections. For example, the optical tracking module may perform beam steering and wavefront extraction without moving parts. In addition, the tracking module may be used in larger optical communication systems that include separate optical assemblies, transceiver modules, and / or modems.

[0012] The optical tracking module may include an optical phased array (OPA) that provides photonic beam control of the output beam. In particular, the OPA may be designed with a limited number of array elements, such as less than 64 elements, to achieve a more compact module while maintaining the ability to perform the corrections described herein. The OPA may include a plurality of phase shifters configured to control signals received by and transmitted from the array elements of the OPA. The OPA may also include a single-path fully reciprocal optical design configured to connect to a transceiver module for receiving and transmitting the optical beam, thereby enabling bidirectional communication via the OPA. The optical tracking module may also include one or more processors, such as application specific integrated circuits (ASICs) or other hardware-based processors, configured to extract signal information of the beam entering from free space via the OPA and provide drive to control the beam exiting from free space via the OPA.

[0013] To control the exit beam, the optical tracking module may include integrated photodetectors, signal processing components, and analog drives. The one or more processors may use the photodetectors and signal processing components to detect and / or determine pointing information associated with the incident beam. The analog drives are configured to steer the exit beam without any physically moving parts. For example, the analog drives may be configured to drive a phase shifter in the OPA to electronically steer the exit beam. The electronic steering may be for tip and tilt of the exit beam. The one or more processors may control the analog drives according to the pointing information, which may be provided in a feedback loop.

[0014] The optical tracking module may also be configured to extract wavefront information using photodetectors and signal processing components. The extracted wavefront information may include tip and tilt terms, as well as higher order terms associated with estimated angle of arrival or other variations in the incident beam. For example, variations in the beam may be caused by environmental disturbances, atmospheric turbulence, or other external factors.

[0015] The configuration of the optical tracking module may allow for a low-cost and compact design. For example, the face of the optical tracking module may be 100 cm 2 and the depth of the optical tracking module may be less than 3 cm.

[0016] The optical tracking module may be used in an overall system architecture for a larger optical communication system, including an optical assembly, a transceiver module, and a modem. The optical assembly may include telescope optics to increase aperture gain and a steerable mirror to maintain a target beam steering range. The transceiver module may include photonics such as filters, multiplexers, demultiplexers, optical amplifiers, variable optical attenuators, and electronic circuits. The components of the transceiver module may be integrated on a single chip. The transceiver chip is configured to receive and process optical beams received by and transmitted from the larger optical communication system. The modem may include an adaptive rate modem with integrated switching capabilities for traffic aggregation and decomposition. In some implementations, the transceiver module may be part of a modem.

[0017] When used as a terminal or node by itself without additional optics or steering, the optical tracking module can be used in a last-mile topology that reduces electromagnetic interference and increases ease of scalability. For example, the last-mile topology can include a relay of point-to-point links configured to distribute data capacity in a "fiber-like" configuration. Each of the point-to-point links can be short-range, such as 100 meters or less, and high-throughput, such as 10 Gbps or more, which can provide higher availability. For example, the higher availability can be 99% or more availability. The links can be placed along roads, which form natural pathways in populated areas. In another example, the last-mile topology can include a point-to-multipoint configuration from a transmitting location on a first building to multiple receiving locations on one or more buildings across the street from the first building. The point-to-multipoint configuration can be achieved by time-sharing of pointing or beamforming between multiple links. In buildings, the network can be extended using inter-building wireless or fiber links.

[0018] The features described herein enable efficient distribution of large network capacity to the "last mile" of connectivity, overcoming capacity bottlenecks that typically limit the cost of radio frequency wireless distribution and fixed fiber infrastructure. The use of optical tracking modules in short-range point-to-point / multipoint relay arrays can avoid logistical issues common to deploying fiber, reduce interference between links, and enable higher throughput. The compact size of the optical tracking modules can enable cheaper and faster deployment, and can facilitate adjustment or updating of the position of the optical tracking modules. Given the characteristics of the output from the optical tracking modules described herein, links in short-range arrays can be more robust to movement of the mounting structure or environmental factors.

[0019] Exemplary System FIG. 1 is a block diagram 100 of an optical tracking module 102 that may be used for short-range high-throughput optical communication links. Additionally, FIG. 2 is a functional flow diagram 200 of the optical tracking module 102. The optical tracking module may include an optical phased array, one or more processors, analog drives, and photodetectors. These components may be part of an integrated circuit or may be discrete components connected to receive an incoming optical beam, process the incoming optical beam, and transmit an outgoing beam. The configuration of the optical tracking module may allow for a low-cost and compact design. For example, the face of the optical tracking module may be 100 cm 2 and the depth of the optical tracking module may be less than 3 cm.

[0020] As shown in FIG. 1, the optical tracking module 102 includes an optical phased array (OPA) 112 that provides photonic beam control of the output beam. The OPA may be a microlens array. The multiple array elements of the OPA 112 may be arranged in a grid pattern with a consistent pitch or distance between adjacent elements. In addition, the OPA 112 may have a limited number of array elements, such as a 32×32 optical array or less. In other examples, the array elements may be in different arrangements with different numbers of rows and columns, different shapes, and / or different pitches (consistent or non-consistent).

[0021] The OPA 112 includes a plurality of phase shifters 113 configured to control signals received by and transmitted from the array elements of the OPA 112. The phase shifters 113 vary the incoming light and / or outgoing light. For example, the phase shifters may be designed to provide amplitude and / or phase adjustment for each one or more outgoing beams. The adjustment provided by the phase shifters may enable multi-beam forming and point-to-multipoint communication. Additionally or alternatively, high bandwidth phase shifter technology may be used to enable fast jumps between adjacent links in point-to-multipoint communication. The incoming light is provided to a photodetector and the outgoing light is provided to the array elements of the OPA 112. The architecture of the multiple phase shifters may include at least one layer of phase shifters with one phase shifter connected to each array element in the multiple array elements. In some examples, the phase shifter architecture includes multiple layers of phase shifters, where the phase shifters in the first layer may be connected in series with one or more phase shifters in the second layer. Each phase shifter in the layer closest to the light source may also be connected to a photodetector.

[0022] The outputs from two or more phase shifters may be combined using a combiner. By using one or more combiners, the incoming light beam is narrowed. The one or more combiners may be 2×2 MMIs or directional couplers. For example, a given combiner may receive two incoming beam portions from a first photodetector at a first input and a second photodetector at a second input and combine the beams into an output beam. The output beam may be directed to a photodetector, an edge coupler, and / or another combiner. In particular, the out-of-phase portion of the output beam may be directed to a photodetector and the remaining portion of the output beam may be directed to an edge coupler or another combiner. The edge coupler may direct the remaining portion of the output beam to an optical fiber for photonic processing.

[0023] In addition, the OPA 112 may be configured to receive light from one or more transmitter components and output the light as a coherent communication beam to be received by a remote communication system. The OPA 112 may also receive light from free space, such as a communication beam from a second communication system, and provide the light to one or more receiver components. For example, the OPA components may provide the necessary photonic processing to couple an incoming light beam into a single mode waveguide that directs the beam from the optical tracking module to a separate transceiver module or modem, etc. The OPA 112 may include a single-path fully reciprocal optical design configured to connect to separate transceiver modules for receiving and transmitting light beams, thereby enabling bidirectional communication via the OPA 112.

[0024] The optical tracking module 102 additionally includes one or more processors 114. The one or more processors 114 may be any conventional processor, such as a commercially available CPU. Alternatively, the one or more processors may be dedicated devices, such as an application specific integrated circuit (ASIC) or other hardware-based processor, such as a field programmable gate array (FPGA). The one or more processors may be configured to extract signal information of the beam entering from free space through the OPA and provide drive to control the beam exiting from free space through the OPA.

[0025] The optical tracking module 102 additionally includes an analog drive 116. The analog drive 116 may adjust the voltage provided to one or more phase shifters 113. For example, the analog drive 116 may include one or more biasing means, such as a bias circuit. The analog drive 116 may adjust the voltage to a set voltage determined by one or more processors 114. Using the analog drive 116, the output beam may be steered without physical moving parts. For example, the analog drive 116 may be configured to drive the phase shifter 113 in the OPA 112 to electronically steer the output beam. The electronic steering may be for tip and tilt of the output beam. The set voltage may be determined by one or more processors according to extracted signal information, which may be provided in a feedback loop.

[0026] The optical tracking module 102 additionally includes a photodetector 118. The photodetector 118 may be one or more photodiodes, photoresistors, phototransistors, or other types of sensors for converting a received light beam or light signal into an electrical signal. In some implementations, the photodetector 118 may be an array of photodetectors. Each photodetector in the array of photodetectors may be connected to one of the phase shifters of the plurality of phase shifters 113. The photodetector 118 may be connected to one or more processors 114 such that an electrical signal generated by the photodetector 118 may be transmitted to the one or more processors 114. Signal processing components between the photodetector 118 and the one or more processors 114 may further process the generated electrical signal to extract signal information. The extracted signal information may include tip and tilt terms, as well as higher order terms associated with power values, intensity values, estimated angle of arrival, or other variations in the incident beam. The variations in the beam may be caused by environmental disturbances, atmospheric turbulence, or other external factors.

[0027] The OPA 112, the processor 114, the analog drive 116, and the photodetector 118 may be integrated circuits, such as the OPA IC 110 of Figure 1. Alternatively, they may be separate components that are connected to provide the functions described herein.

[0028] In some implementations, the optical tracking module may include a voltage regulator. The voltage regulator may be connected to an external power source and / or a separate computing device. In other implementations, the optical tracking module may include thermal management components, such as one or more temperature sensors for detecting the temperature at or near the optical tracking module. As shown in FIGS. 1 and 2, the optical tracking module 102 includes a voltage regulator 122 and a temperature sensor 124. The voltage regulator 122 and the temperature sensor 124 are shown in FIG. 1 on the same printed circuit board (PCB) 120 as the OPA IC 110. In other implementations, the voltage regulator and the temperature sensor may be on a separate board or other support base from the OPA, processor, analog drive, and photodetector. The voltage regulator 122 is connected to an external power source and / or a computing device separate from the optical tracking module 102 via a module port 144.

[0029] The optical tracking module may optionally include a circulator, such as circulator 130 on the optical tracking module 102, or may be connected to an external circulator. The circulator may have a first port configured to receive signals from a computing device separate from the optical tracking module via a first fiber, a second port configured to send signals to and receive signals from the OPA, and a third port configured to send signals to the separate computing device via a second fiber. As shown in FIG. 1, there may be a fiber input at a first module port 140 that is directed to the first port of the circulator 130, and a fiber output from a second module port 142 is connected to the third port of the circulator 130. The fiber input and fiber output may be connected to a separate computing device, such as a modem.

[0030] As shown in FIG. 2, the components of the optical tracking module may be divided into several blocks. The optical tracking module 102 may include, for example, a photonics block 202, a transmit / receive block 204, a control block 206, and a digital control interface 208. The photonics block 202 includes at least an OPA 112, a phase shifter 113, a photodetector 118, and a temperature sensor 124. The transmit / receive block 204 comprises a portion of an integrated circuit that processes input or output signals from the photonics block 202. For example, a first signal generated by the photodetector 118 may be directed to a first amplifier 212 and an analog-to-digital converter (ADC) 222 before being directed to the control block 206. A second signal from the control block 206 may be directed to a digital-to-analog converter (DAC) 220 and a second amplifier 210 before being directed to the phase shifter 113. The control block 206 may include one or more processors 114, such as a digital signal processor as shown in Figure 2, another type of integrated circuit, or one or more discrete components. The digital control interface 208 may be a low speed control digital interface 230 as shown in Figure 2. The digital control interface 208 may be configured to monitor sensor measurements from the optical tracking module, such as telemetry data, and / or perform programming for the optical tracking module, such as initialization or updates.

[0031] 3 shows an optical tracking module 102 in communication with another optical tracking module 302 via a communication link 22. As depicted, the optical tracking module 102 described herein can transmit and receive signals in a short-range high-throughput free-space optical communication link without additional optics or steering components. As shown in FIG. 1, the optical tracking module 102 can function as such when connected to a fiber input, a fiber output, and power. The communication link 22 is shown in FIG. 3 as including a first optical beam 20a transmitted by the module 102 to the optical tracking module 302 and a second optical beam 20b transmitted by the optical tracking module 302 to the optical tracking module 102.

[0032] The optical tracking module 302 may be configured the same as or similar to the optical tracking module 102, as described herein. For example, the optical tracking module 302 includes an OPA IC 310 having an OPA 312, a phase shifter 313, one or more processors 314, an analog drive 316, and a photodetector 318, which may be equivalent to the OPA IC 110, the OPA 112, the phase shifter 113, one or more processors 114, the analog drive 116, and the photodetector 118. The optical tracking module 302 may also include a voltage regulator 322 that is the same as or similar to the voltage regulator 122, and a temperature sensor 324 that is the same as or similar to the temperature sensor 124. These components of the optical tracking module 302 may be located on a PCB 320 that is the same as or similar to the PCB 120. In some implementations, the optical tracking module 302 may also include a circulator in the same or similar manner as the circulator 130.

[0033] The communication link 22 between the first tracking module 102 and the second tracking module 302 may be formed when the tracking modules are aligned. Alignment may be determined by determining when a line of sight is established between the tracking modules 102, 302 using the light beams 20a, 20b. Using the communication link 22, the one or more processors 114 may send communication signals to the second tracking module 302 through free space using the light beam 20a, and the one or more processors 314 may send communication signals to the first tracking module 102 through free space using the light beam 20b. The communication link 22 between the first and second tracking modules 102, 302 allows for bidirectional transmission of data between the two tracking modules. Notably, the communication link 22 in these examples may be a free-space optical communication (FSOC) link. In other implementations, one or more of the communication links 22 may be radio frequency communication links or other types of communication links capable of traveling through free space. In some other implementations, the communications link 22 may be unidirectional and / or two or more beams may be transmitted from one optical tracking module to another optical tracking module.

[0034] As shown in Figures 4A and 4B, the optical tracking module may additionally or alternatively be used in an overall modular system architecture for a long-distance optical communication system that includes an optical assembly, a transceiver module, and a modem. The modem may be configured to provide higher transmission and collection power than the modem used to power the optical tracking module itself. In Figures 4A and 4B, the architecture of an optical communication system 400 is depicted as including an optical assembly 404, a transceiver module 410, and a modem 416. Another optical communication system 430 is depicted in Figure 4A as including an optical assembly 434, a transceiver module 440, and a modem 446. The optical communication system 400 is shown to communicate with the optical communication system 430 via a communication link 22.

[0035] The optical assembly 404 may include telescope optics to increase the aperture gain. For example, the optical communication system 400 includes one or more lenses 406 forming a telescope. The telescope may receive collimated light and output collimated light. The telescope may include an objective portion, an eyepiece portion, or a relay portion. As shown in FIG. 4B, the system may include an objective lens 470, an eyepiece lens 472, and relay lenses 474, 476.

[0036] The optical assembly 404 may also include one or more additional steering mechanisms 408, such as an actuating / steering mirror 482, to maintain a target beam steering range. The actuating / steering mirror 482 may be a MEMS two-axis mirror, a two-axis voice coil mirror, or a piezoelectric two-axis mirror. When the optical assembly 404 is connected to the optical tracking module 102, the one or more processors 114 of the optical tracking module 102 may be configured to adjust the pointing direction and / or wavefront shape of the output beam by controlling the OPA IC 110 and / or the mirror 482. In some examples, the one or more processors 114 may receive and process additional signals from the optical assembly 404, such as from one or more sensors disposed on the optical assembly. In alternative implementations, the one or more additional processors may be dedicated to receiving and controlling the steering mirrors of the optical assembly 404. Using a feedback loop, the steering mechanism 408 may be controlled as a fast steering mirror or a coarse pointing mirror.

[0037] The transceiver module 410 may include transmitter components, such as a light source for providing an outgoing beam, and receiver components, such as a sensor for processing an incoming beam. As shown in FIG. 4A and FIG. 4B, the transceiver module 410 includes a seed laser 412 and a sensor 414. The seed laser 412 may be a distributed feedback laser (DFB), a light-emitting diode (LED), a laser diode, a fiber laser, or a solid-state laser. The optical output or optical signal of the seed laser 412 may be controlled by a current or an electrical signal applied directly to the seed laser, such as from a modulator that modulates a received electrical signal. The light transmitted from the seed laser 412 is received by the OPA 112. Other transmitter components may include an amplifier, such as a high-power semiconductor optical amplifier.

[0038] The receiver components may include at least a sensor 414, such as an additional photodetector. In the same or similar manner as the photodetector 118, the sensor 414 may convert the received light or optical signals into electrical signals that may be further processed by one or more processors of the optical tracking module, the modem 416, or other portions of the communication system 400. Other receiver components may include an attenuator, such as a variable optical attenuator, an amplifier, such as a semiconductor optical amplifier, or a filter.

[0039] The transceiver module 410 may include additional photonics, different combinations of photonics, and / or electronic circuitry. The components of the transceiver module may be integrated on a single chip. Alternatively, the transceiver module may comprise two or more chips and / or separate components. The transceiver module 410 is configured to transmit and receive optical beams via the optical tracking module 102 and to communicate with the modem 416. In some implementations, the transceiver module may be part of an overall modem module.

[0040] The modem 416 may include an adaptive rate modem with integrated switching capabilities for traffic aggregation and disaggregation. The components of the modem 416 may be configured to provide physical layer extensions, as well as digital processing for communication protocols and switching logic. For example, the components may include an integrated Ethernet switch for aggregating / disaggregating different input / output traffic sources, a framer function for encapsulating Ethernet packets and other data sources into frames optimized for transmission over a wireless optical link, a coding rate selectable forward error correction (FEC) encoding / decoding function whose rate may be selected based on channel conditions, a scrambling / unscrambling function for randomization of data that may provide good DC balance and aid in clock recovery, an automatic repeat request function for rapid recovery of lost packets by using retransmissions, baud rate and / or modulation adaptation based on channel conditions, or logic for point-to-multipoint communication support through a scheduler and medium access control. As shown in FIG. 4A, the modem 416 may include one or more processors 418, memory 420, data 422, and instructions 424.

[0041] The one or more processors 418 may be any conventional processor, such as a commercially available CPU. Alternatively, the one or more processors may be dedicated devices, such as application specific integrated circuits (ASICs) or other hardware-based processors, such as field programmable gate arrays (FPGAs). Although FIG. 4A functionally illustrates the one or more processors 418 and memory 420 as being within the same block, such as within the modem 416, the one or more processors 418 and memory 420 may actually comprise multiple processors and memories that may or may not be housed within the same physical enclosure, such as within both the modem 416 and a separate processing unit. Thus, reference to a processor or computer will be understood to include reference to a collection of processors or computers or memories that may or may not operate in parallel.

[0042] The one or more processors 418 may be in communication with the transceiver module 410. In particular, the one or more processors 418 may be configured to receive and process incoming optical signals and provide instructions to the transceiver module 410 for transmitting optical signals. Thus, the one or more processors 418 may be configured to transmit data in signals via a transmitter component and to receive communications and data in signals via a receiver component. The received signals may be processed by the one or more processors 418 to extract the communications and data. Additionally or alternatively, the received signals may be processed by the one or more processors 418 to direct the received signals to a next hop or client interface.

[0043] The memory 420 may store information accessible by one or more processors 418, including data 422 and instructions 424 that may be executed by the one or more processors 418. The memory may be of any type capable of storing information accessible by a processor, including computer readable media such as hard drives, memory cards, ROM, RAM, DVDs, or other optical disks, as well as other writable and read-only memories. Systems and methods may include different combinations of the foregoing, whereby different portions of the data 422 and instructions 424 are stored on different types of media.

[0044] The data 422 may be retrieved, stored, or modified by one or more processors 418 according to the instructions 424. For example, the data 422 may be stored in a computer register of a relational database as a table with multiple different fields and records, an XML document, or a flat file, although the systems and methods are not limited by any particular data structure. The data 422 may be formatted in any computer readable format, such as, but not limited to, binary values ​​or Unicode. By way of further example only, image data may be stored as a bitmap, which consists of a grid of pixels stored according to a format that is compressed or uncompressed, lossless (e.g., BMP) or lossy (e.g., JPEG), and bitmap or vector-based (e.g., SVG), as well as computer instructions for rendering graphics. The data 422 may include any information sufficient to identify the associated information, such as a number, a descriptive text, a dedicated code, a reference to data stored in other areas of the same or different memory (including other network locations), or information used by a function to calculate the associated data. In some implementations, the data 422 may include calibration information, such as one or more offsets determined for tracking a signal, communication protocol data, and / or switching logic data.

[0045] The instructions 424 may be any set of instructions (such as machine code) or instructions (such as scripts) that are executed directly or indirectly by one or more processors 418. For example, the instructions 424 may be stored as computer code on a computer-readable medium. In this regard, the terms "instructions" and "program" may be used interchangeably herein. The instructions 424 may be stored in object code format for direct processing by one or more processors 418, or in any other computer language including a script or a collection of independent source code modules that are interpreted on demand or precompiled. The functions, methods, and routines of the instructions 424 are described in more detail below. The instructions may include calibration instructions, communication protocol instructions, and / or switching logic instructions.

[0046] The system may include additional components that support the functionality of the communications terminal. For example, the system may include optical fibers or waveguides that connect the optical components and create paths between the transceiver module 410, the optical tracking module 102, and the optical assembly 404, or vice versa.

[0047] 4A, the second communication system 430 includes the optical tracking module 302, an optical assembly 434, a transceiver module 440, and a modem 446. The optical tracking module 302 may be the same as or similar to the optical tracking module 102. The optical assembly 434 may be the same as or similar to the optical assembly 404, such as including one or more lenses 436 and steering mechanism 438 comparable to the one or more lenses 406 and steering mechanism 408. The transceiver module 440 may be the same as or similar to the transceiver module 410, such as including a seed laser 442 and a sensor 444 comparable to the seed laser 412 and sensor 414. The modem 446 may be the same as or similar to the modem 416, such as including one or more processors 448, memory 450, data 452, and instructions 454 comparable to the one or more processors 418, memory 420, data 422, and instructions 424. Additional components to support the functionality of communication system 430 may be included similar to the additional components described above for communication system 400. In addition, communication system 430 may have a system architecture that is the same as or similar to the system architecture of communication system 400 shown in FIG.

[0048] The communication link 22 between the first communication system 400 and the second communication system 430 may be formed when the first and second communication devices are aligned. The alignment may be determined by determining when a line of sight is established between the communication systems 400, 430 using the optical beams 20a, 20b. In particular, a line of sight alignment may exist between the optical assembly 404 of the first communication system 400 and the optical assembly 434 of the second communication system 430. Using the communication link 22, the one or more processors 114 and / or 418 may transmit communication signals to the second communication system 430 through free space using the optical beam 20a, and the one or more processors 314 and / or 448 may transmit communication signals to the first communication system 400 through free space using the optical beam 20b. The communication link 22 between the first and second communication systems 400, 430 allows for bidirectional transmission of data between the two systems. In particular, the communication links 22 in these examples may be free space optical communication (FSOC) links. In other implementations, one or more of the communication links 22 may be radio frequency communication links or other types of communication links capable of traveling through free space. In some other implementations, the communication 22 may be unidirectional and / or two or more beams may be transmitted from one optical tracking module to another optical tracking module.

[0049] 5 and 6A show a network portion 500 comprising multiple optical tracking modules 102, 302, 520, 522, 524, 526, 528, and 530 as network nodes or terminals. The optical tracking modules 520, 522, 524, 526, 528, and 530 may be configured in the same or similar configuration as the optical tracking modules 102 and 302. The optical tracking modules in the network portion 500 may communicate with two adjacent nodes, as shown by the arrows in FIG. 5 and the solid lines in FIG. 6A. The optical tracking modules may communicate with each other via one or more communication links, such as the communication link 22 between the optical tracking modules 102 and 302. Each of the point-to-point links may be short-range, such as 100 meters or less, and high-throughput, such as 10 Gbps or more, which may provide higher availability. In other implementations, such as in areas of lower demand or lower density, the point-to-point links may have a greater distance, such as 500 meters, and a lower throughput, such as 1-10 Gbps.

[0050] The network portion 500 is a last-mile topology comprising a relay of point-to-point links configured to distribute data capacity in a "fiber-like" configuration throughout a geographic area. The optical tracking module 524 may be connected to a backhaul link 546 to provide connectivity to at least the geographic area served by the network portion 500. The network portion 500 may be connected to a larger network, such as the Internet, and may be configured to provide client devices with access to resources stored on or provided through the larger computer network. One or more of the optical tracking modules 102, 302, 520, 522, 524, 526, 528, 530 may be connectable to a remote device directly or through an access point. For example, the optical tracking module 102 communicates directly with a client device 540, the optical tracking module 520 communicates directly with a server device 544, and the optical tracking module is connected to an access point 542 through which a client device may be connected to the network portion 500.

[0051] In some implementations, network portion 500 may act as an access network for client devices such as mobile phones, laptop computers, desktop computers, wearable devices, tablet computers, etc. In other implementations, network portion 500 may provide access to server computing devices or to other devices within network portion 500 through backhaul links 546.

[0052] As shown in FIG. 6A, the links may be located along roads that form natural paths in populated areas. These natural paths include the unobstructed line-of-sight paths required for effective free-space optical communication. Each of the optical tracking modules 102, 302, 520, 522, 524, 526, 528, 530 is mounted on a building along the road. In another example, the last mile topology may include a point-to-multipoint configuration from a transmitting location on a first building to multiple receiving locations on one or more buildings across the street from the first building. As shown in FIG. 6B, the point-to-multipoint configuration may be between the optical tracking modules 526 and 528 and between the optical tracking modules 528 and 530. One or more processors of the optical tracking module 526 may modify the irradiance or phase of one or more phase shifters to form a multipoint beam pattern or time division pointing the link between the optical tracking modules 526 and 528. One or more processors of the optical tracking module 528 may modify the irradiance or phase of one or more phase shifters to form a multi-point beam pattern or time division pointing link between the optical tracking modules 528 and 530.

[0053] In a building, the network may be extended using intra-building wireless or fiber links. For example, a given optical tracking module in the network portion 500 may be connected by wireless or fiber link to an Ethernet switch, router, or hub in the building in which it is installed. The switch, router, or hub may then be connected to intra-building nodes and / or access points in the building that are accessible by client devices in the building. The optical tracking modules described herein may also be used for such intra-building wireless links or access points. In other implementations, the intra-building nodes and / or access points include non-optical communication technologies, such as radio frequency technologies.

[0054] In some examples, additional optical tracking modules may be deployed and added to an existing network, and an existing network may be updated to include additional optical tracking modules. For example, as shown in FIG. 6A, additional optical tracking modules 620 and 622 may be deployed after network portion 500 is installed and operational. Optical tracking module 620 is located between optical tracking modules 302 and 520, and optical tracking module 622 is located between optical tracking modules 520 and 522. One or more processors may reconfigure the network to include links between optical tracking modules 302 and 620, between optical tracking modules 620 and 520, between optical tracking modules 520 and 622, and between optical tracking modules 622 and 522. Links between optical tracking modules 302 and 520 and between optical tracking modules 520 and 522 may be removed, reduced, or maintained. Additional optical tracking modules deployed in the network may increase coverage where additional bandwidth is needed based on population density or usage history. Additionally or alternatively, additional optical tracking modules can be deployed to extend network portions along roads and into previously uncovered geographic areas.

[0055] The network portion 500 shown in Figures 5, 6A and 6B is merely illustrative, and in some implementations, the network portion 500 may include additional or different communication terminals. For example, in other networks, one or more of the nodes may comprise a communication system, such as communication system 400 or 430, of which the optical tracking module is a part, or other types of optical terminals. However, using the optical tracking module described herein as a terminal or node by itself, without additional optics or steering, offers advantages over larger or more traditional optical terminals in the last mile topology of the network. That is, the optical tracking module can reduce electromagnetic interference and increase ease of scalability.

[0056] Exemplary Methods In operation, the one or more processors 114 may control an optical phased array for free-space optical communication. In FIG. 7, a flow diagram 700 is shown according to some of the aspects described above that may be performed by the one or more processors 114 of the first optical tracking module 102 and / or the one or more processors 314 of the second optical tracking module 302. Additionally or alternatively, one or more steps in the flow diagram 700 may be performed by one or more processors 418 or 448 of a modem or other dedicated processor that is part of the communication system 400 or 430. Although FIG. 7 shows blocks in a particular order, the order may be changed and multiple operations may be performed simultaneously. Also, operations may be added or omitted.

[0057] In block 702, a first optical communication beam is received at an optical phased array in an integrated circuit, such as OPA IC 110 of the optical tracking module 102. The first optical communication beam may carry data from a remote optical terminal or client device. In particular, the first optical communication beam may be received at multiple array elements of an OPA, such as OPA 112, and directed to a photodetector in the integrated circuit, such as photodetector 118. In some examples, the first optical communication beam is first directed through one or more phase shifters, such as phase shifter 113, before being directed to the photodetector. In some implementations, the beam portion received at a given array element may be directed through at least one phase shifter. At least a portion of each beam portion may be directed to a photodetector. Additionally or alternatively, at least a portion of each beam portion may be coupled to a waveguide that directs the collected beam portion to the photodetector, such as via an edge coupler. For example, optical beam 20b may be received at an optical phased array in OPA 112 of the optical tracking module 102. The light beam 20 b may be directed through a phase shifter 113 and coupled into a single mode waveguide that directs the light beam to a photodetector 118 .

[0058] At block 704, the first optical communication beam is received at a photodetector of the integrated circuit, such as photodetector 118. At block 706, a first signal is generated at the photodetector based on the first optical communication beam. The first signal may be related to the phase, power, or intensity of the first optical communication beam at the photodetector. In some implementations, the photodetector may generate a signal for different locations on the photodetector, where each location may correspond to or approximate a beam portion received at a given array element of the OPA.

[0059] At block 708, one or more processors in the integrated circuit, such as the one or more processors 114, determine signal information of the first optical communications beam according to the first signal. The signal information may include a phase value of the optical communications beam received at the optical detector. For example, the one or more processors 114 may determine phase values ​​at various locations on the optical detector 118 based on a signal generated at the optical detector 118. The phase values ​​may be used by the one or more processors to determine a phase front of the first optical communications beam. Determining the phase front may include detecting a phase shift setting for each phase shifter. Alternatively, the signal information may include a power value or intensity value of the optical communications beam received at the optical detector. Based on the signal information, the one or more processors 114 may determine an angle of arrival of the first optical communications beam. The angle of arrival may be determined in terms including tip, tilt, or higher order terms. Additionally or alternatively, the one or more processors 114 may determine an amount of power received at the optical detector, which may be related to an amount of out-of-phase beam portions.

[0060] At block 710, the one or more processors may send a second signal to adjust one or more phase shifters in the integrated circuit, such as phase shifter 113, based on the determined signal information. For example, the signal information may indicate that there is a wavefront error that reduces the coupling efficiency of the first communication beam received at the OPA 112, which may also affect the coupling efficiency of the second communication beam transmitted from the OPA 112 to the remote optical terminal. The one or more processors 114 may then send a second signal to adjust the one or more phase shifters 113. The adjustments may correspond to tip, tilt, and / or higher order terms determined for the angle of arrival of the first optical communication beam. In some implementations, the adjustments may improve coupling by increasing the in-phase portion of the output beam at a given combiner while decreasing the out-of-phase portion of the output beam at a given combiner. The closer the out-of-phase portion of the output beam is to zero intensity, the better the coupling to the in-phase portion of the output beam and therefore to the remainder of the receive path.

[0061] Alternatively, the adjustment may correspond to the difference between the location of the maximum power or intensity of the first optical communication beam on the photodetector 118 and the location of the zero point of the photodetector 118. The second signal may be sent to an analog drive of the integrated circuit, such as the analog drive 116, which may then apply a drive to adjust one or more phase shifters. The drive may include applying different amounts of voltage or current to adjust the phase shifters, or may use another biasing means.

[0062] In block 712, the one or more processors may transmit a second optical communication beam using the OPA and one or more phase shifters. For example, the one or more processors 114 may transmit the optical beam 20a using the OPA 112 and phase shifter 113 of the OPA IC 110 after the phase shifter 113 is adjusted by the analog drive 116. Predistortion of the wavefront and pointing direction based on the locally adjusted phase shifter may enable maximizing power coupling in the opposite direction across the communication link due to reciprocity of beam propagation through the atmosphere. In some implementations, the second optical communication beam may be transmitted while one or more of the other steps described in this exemplary method are being performed.

[0063] The blocks shown in Figure 7 may comprise a feedback loop for tracking changes in one or more received optical communication beams at the optical tracking module 102. The changes may include position changes such as drift, fading or scintillation, or other types of changes, such as those due to atmospheric turbulence. Additionally or alternatively, the feedback loop may be iterated to minimize the power measured in the out-of-phase portions received at the photodetectors. The feedback loop may include making a phase shifter adjustment at each cycle.

[0064] The features described herein enable efficient distribution of large network capacity to the "last mile" of connectivity, overcoming capacity bottlenecks that typically limit the cost of radio frequency wireless distribution and fixed fiber infrastructure. The use of optical tracking modules in short-range point-to-point relay arrays can avoid logistical issues common to deploying fiber, reduce interference between links, and enable higher throughput. The compact size of the optical tracking modules can enable cheaper and faster deployment, and can facilitate adjustment or updating of the position of the optical tracking modules. Given the characteristics of the output from the optical tracking modules described herein, links in short-range arrays can be more robust to movement of the mounting structure or environmental factors.

[0065] Unless otherwise stated, the above alternatives are not mutually exclusive and can be implemented in various combinations to achieve unique advantages. These and other variations and combinations of the features discussed above can be utilized without departing from the subject matter defined by the claims, and the above description of the embodiments should be interpreted as illustrations, not as limitations of the subject matter defined by the claims. In addition, the provision of examples described herein, as well as expressions such as "such as," "including," and the like, should not be interpreted as limiting the subject matter of the claims to specific examples, but rather, these examples are intended to illustrate only one of many possible embodiments. Moreover, the same reference symbols in different drawings may identify the same or similar elements.

Claims

1. 1. An optical tracking module, comprising:

1. An optical phased array (OPA), comprising: A plurality of array elements; an optical phased array (OPA) including a plurality of phase shifters; an analog drive configured to adjust the plurality of phase shifters; an integrated photodetector configured to receive light from the OPA; One or more processors, Extracting signal information of an incident beam via the OPA; and controlling the output beam using the analog drive based on the signal information. An optical tracking module, wherein the OPA, the analog drive, the integrated photodetector, and the one or more processors are within an integrated circuit.

2. The optical tracking module of claim 1 , wherein the optical tracking module is configured to connect to a modem via one or more fibers.

3. 3. The optical tracking module of claim 2, further comprising a circulator including a first port configured to receive a signal from a first fiber, a second port configured to transmit a signal to the integrated circuit and receive a signal from the integrated circuit, and a third port configured to transmit a signal to the second fiber.

4. The optical tracking module of claim 1 further comprising a voltage regulator.

5. The optical tracking module of claim 4 , wherein the voltage regulator is configured to provide power to the integrated circuit.

6. The optical tracking module of claim 1 , wherein the optical tracking module is configured to communicate telemetry data to one or more separate processors external to the optical tracking module.

7. The optical tracking module of claim 1 , wherein the optical tracking module is configured to connect to a separate optical lens assembly that increases aperture gain.

8. The optical tracking module of claim 7 , wherein the optical tracking module is configured to connect to a separate transceiver module that includes one or more transceivers and one or more amplifiers.

9. The optical tracking module has a volume of 1000 cm ３ The optical tracking module of claim 1 .

10. The optical tracking module has a surface area of ​​100 cm ２ The optical tracking module of claim 9 .

11. The optical tracking module of claim 1 , wherein the plurality of array elements is a 32×32 array.

12. the analog drive includes a digital-to-analog converter (DAC) and an amplifier; the one or more processors are coupled to the DAC; the DAC is also connected to the amplifier; The optical tracking module of claim 1 , wherein the amplifier is also connected to the OPA.

13. The optical tracking module of claim 1 , wherein the integrated photodetector is connected to the one or more processors via an amplifier and an analog-to-digital converter (ADC).

14. 1. A system comprising: a plurality of communication terminals in a network arrangement including a plurality of point-to-point relay links; Each of the plurality of communication terminals includes an optical tracking module, the optical tracking module comprising:

1. An optical phased array (OPA), comprising: A plurality of array elements; an optical phased array (OPA) including a plurality of phase shifters; an analog drive configured to adjust the plurality of phase shifters; an integrated photodetector configured to receive light from the OPA; One or more processors, Extracting signal information of an incident beam via the OPA; and controlling the output beam using the analog drive based on the signal information. wherein each of the plurality of communications terminals is lensless except for the OPA.

15. each communication terminal of the plurality of communication terminals is located within 100 meters of another communication terminal of the plurality of communication terminals; 15. The system of claim 14, wherein each communication terminal of the plurality of communication terminals has a throughput of at least 10 Gbps to another communication terminal of the plurality of communication terminals.

16. The system of claim 14 , wherein the network arrangement also includes one or more point-to-multipoint links.

17. The system of claim 14 , wherein the network arrangement at least partially comprises a mesh arrangement.

18. The system of claim 14 , wherein the network arrangement at least partially comprises a ring arrangement.

19. The system of claim 14 , wherein the plurality of point-to-point relay links includes at least one inter-building link.

20. 1. A method for controlling an optical phased array, comprising: Receiving a first optical communications beam at the optical phased array in an integrated circuit; receiving the first optical communication beam at a photodetector within the integrated circuit; generating a first signal at the optical detector based on the first optical communication beam; determining, by one or more processors within the integrated circuit, signal information of the first optical communication beam according to the first signal; sending, by the one or more processors, a second signal to adjust one or more phase shifters within the integrated circuit based on the determined signal information; transmitting a second optical communications beam using the optical phased array and the one or more phase shifters.

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